Temporal sampling in a wearable breath analyser

Abstract

Systems and methods are disclosed for temporal sampling of air exhaled by a user. Some embodiments comprise a mask adapted to be worn by a user, a chamber, disposed in or on the mask, the chamber comprising a valve, at least one sensor, disposed in the chamber, for measuring composition of air, an actuator adapted to open the valve, and at least one processor. The at least one processor is programmed to selectively instruct the actuator to open the valve, thereby causing air in the mask to be exposed to the at least one sensor, at a time associated with exhalation by the user, and to selectively instruct the actuator to close the valve, thereby preventing air from entering the chamber, at a time associated with inhalation by the user.

What is claimed is: 
     
         1 . A system comprising:
 a mask adapted to be worn by a user;   a chamber, disposed in or on the mask, the chamber comprising a valve;   at least one sensor, disposed in the chamber, for measuring composition of air;   an actuator adapted to open the valve; and
 at least one processor programmed to: 
   selectively instruct the actuator to open the valve, thereby causing air in the mask to be exposed to the at least one sensor, at a time associated with exhalation by the user; and   selectively instruct the actuator to close the valve, thereby preventing air from entering the chamber, at a time associated with inhalation by the user.   
     
     
         2 . The system of  claim 1 , wherein the at least one processor is programmed to selectively instruct the actuator to open the valve at a time which at least partially coincides with exhalation by the user. 
     
     
         3 . The system of  claim 2 , wherein the at least one processor is programmed to selectively instruct the actuator to open the valve at a time which at least partially coincides with a start of exhalation by the user. 
     
     
         4 . The system of  claim 1 , wherein the at least one processor is programmed to determine a difference between air pressure in the mask and air pressure outside the mask, and to determine based on the pressure difference that exhalation by the user is occurring. 
     
     
         5 . The system of  claim 1 , wherein the at least one processor is programmed to determine a first time at which exhalation by the user begins, and to selectively instruct the actuator to open the valve a predetermined interval after the first time. 
     
     
         6 . The system of  claim 5 , wherein the at least one processor is programmed to select the predetermined interval so that the air in the mask that is caused to be exposed to the at least one sensor does not originate at a dead volume. 
     
     
         7 . The system of  claim 1 , wherein:
 the mask is adapted to be worn by a user having a repetitive breathing cycle, each breathing   cycle comprising inhalation and exhalation by the user;   the at least one processor is programmed to selectively instruct the actuator to open the valve at times associated with exhalation during a plurality of breathing cycles; and   the interval varies for each of the plurality of breathing cycles.   
     
     
         8 . The system of  claim 7 , wherein the at least one processor is programmed to:
 increase the interval for each of the plurality of breathing cycles; and   determine one or more particular properties of breath exhaled by the user in each of the plurality of breathing cycles.   
     
     
         9 . The system of  claim 8 , wherein the one or more particular properties that the at least one processor is programmed to determine comprises CO 2  concentration in the breath exhaled by the user in each breathing cycle. 
     
     
         10 . The system of  claim 1 , wherein the at least one processor is programmed to selectively instruct the actuator to close the valve after a duration of time associated with exhalation by the user has passed since the valve was opened. 
     
     
         11 . The system of  claim 10 , wherein the at least one processor is programmed to determine a rate of air flow from inside of the mask to outside of the mask as a result of exhalation by the user, and to determine the duration of time based on the rate of air flow, so that the valve is closed prior to the end of exhalation by the user. 
     
     
         12 . The system of  claim 11 , wherein:
 the mask is adapted to be worn by a user having a repetitive breathing cycle, each comprising inhalation and exhalation by the user;   the at least one processor is programmed to selectively instruct the actuator to open the valve at times associated with exhalation during a plurality of breathing cycles; and   the duration of time is the same for each of the plurality of breathing cycles.   
     
     
         13 . The system of  claim 1 , wherein the mask is devoid of separate passageways for air to be inhaled by the user and air exhaled by the user. 
     
     
         14 . The system of  claim 1 , wherein the actuator comprises:
 at least one electromagnetic element;   at least one hinge; and   a lever adapted to rotate about the at least one hinge;   wherein the electromagnetic element is adapted to supply a force to the lever, causing the lever to rotate about the at least one hinge and open the valve.   
     
     
         15 . The system of  claim 1 , wherein the valve comprises an element adapted to supply an elastic force tending to close the valve when not opened by the actuator. 
     
     
         16 . A method of measuring breath composition by a user, the method being for use in a system comprising a chamber, the chamber having a valve and at least one sensor for measuring composition of air, the system comprising at least one processor and an actuator adapted to open and close the valve, the method comprising acts of:
 (A) the at least one processor selectively instructing the actuator to open the valve, thereby causing respiratory air to be exposed to the at least one sensor, at a time associated with exhalation by the user; and   (B) the at least one processor selectively instructing the actuator to close the valve, thereby preventing air from entering the chamber, at a time associated with inhalation by the user.   
     
     
         17 . The method of  claim 16 , wherein the act (A) comprises the at least one processor selectively instructing the actuator to open the valve at a time which at least partially coincides with exhalation by the user. 
     
     
         18 . The method of  claim 17 , wherein the act (A) comprises the at least one processor selectively instructing the actuator to open the valve at a time associated with a start of exhalation by the user. 
     
     
         19 . The method of  claim 16 , comprising acts, performed prior to the act (A), comprising:
 determining an air pressure at one or more locations along the path of respiratory air flow; and   determining based on the pressure that exhalation by the user is occurring.   
     
     
         20 . The method of  claim 16 , wherein the act (A) comprises:
 determining a first time at which exhalation by the user begins; and   the at least one processor selectively instructing the actuator to open the valve a predetermined interval after the first time.   
     
     
         21 . The method of  claim 20 , wherein the act (A) comprises:
 determining a rate of air flow as a result of exhalation by the user; and   determining the interval based at least in part on the rate of air flow.   
     
     
         22 . The method of  claim 20 , wherein the act (A) comprises selecting the predetermined interval at least in part so that the respiratory air that is selectively caused to be exposed to the at least one sensor does not originate at a dead volume. 
     
     
         23 . The method of  claim 16 , wherein:
 the user has a repetitive breathing cycle, each breathing cycle comprising inhalation and exhalation by the user;   the act (A) is performed for a plurality of breathing cycles; and   the interval varies for each of the plurality of breathing cycles.   
     
     
         24 . The method of  claim 23 , wherein:
 the interval increases for each of the plurality of breathing cycles; and   the act (A) comprises detecting one or more particular properties of breath exhaled by the user in each of the plurality of breathing cycles.   
     
     
         25 . The method of  claim 24 , wherein the one or more particular properties detected in the act (A) comprises CO2 concentration in the breath exhaled by the user in each breathing cycle. 
     
     
         26 . The method of  claim 16 , wherein the act (B) comprises the at least one processor selectively instructing the actuator to close the valve after a duration of time associated with exhalation by the user has passed since the valve was opened. 
     
     
         27 . The method of  claim 26 , wherein the act (B) comprises:
 determining a rate of air flow as a result of exhalation by the user; and   determining the duration of time based on the rate of air flow, so that the duration of time terminates prior to the end of exhalation by the user.   
     
     
         28 . The method of  claim 26 , wherein:
 the user has a repetitive breathing cycle, each comprising inhalation and exhalation by the user;   the acts (A) and (B) are performed for a plurality of breathing cycles; and   the duration of time varies for each of the plurality of breathing cycles.   
     
     
         29 . The method of  claim 16 , wherein the system is devoid of separate passageways for air to be inhaled by the user and air exhaled by the user.